Thread: Water heater Pilot light blowing out

I have a client who is having a problem with the pilot light on a WH blowing out. Strange thing is he can light it in the morning and it will stay lit till late afternoon. Something is causing it to blow out, and then when he attempts to relight it in the afternoon, the pilot will not light.

I just assumed that he had a problem with the thermocouple or a venting issue.

I read an article below I found on the web and admit I had not ever seen where a manufacture recommend not placing a WH in the attic where any type of power ventilation is present.

"If the light keeps going out after you take these precautions, perhaps there's a fan in the attic that's blowing it out. Water-heater manufacturers typically recommend not placing a water heater in an attic where there is any sort of power ventilation, including gable fans, power roof vents, and whole-house fans. *Also, make sure your bathroom exhaust fan is connected to ductwork that vents to the outside; you'd be amazed at how many times I've seen these fans blowing air directly into an attic. If fans are at fault, you'll need to equip your heater with separate ductwork to ensure that it gets a dedicated supply of combustion air."

Any comments?

rick

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Rick,

Gremlins. For sure.

OK, really. When you say it can't be relit, do you mean that it lights but won't stay lit or no gas to the pilot with the button depressed? Is this one of the new sealed burner type?

Normally, I would guess thermocouple if the pilot lights but does not stay lit.

How about a new installation and debris in the gas line to the pilot"

Possibly a faulty control valve assembly.

Does it sound like I am guessing? Yep. I'm going back to gremlins.

That's interesting.... I imagine the newer 'explsion resistant' type don't have that problem since the pilot is sealed. Or, at least sealed off from the air around the tank. If a draft is being pulled down the vent I suppose it could blow the light out just the same.

Rick, I could see a whole house (what we used to call attic fans) that would move enough air to disturb a w/h, but unless it was really close to a very powerful attic ventilator, I doubt it.
Heck, when was the last time you actually felt ANY air moving in an attic around here?
I am guessing it has more to do with a weak thermocouple or if one of the sealed combustion units, the pilot sensor assembly may need to be cleaned.
Sounds like the problem is temperature related, but beyond that I in there with Gunnar, just guessing.

Supposedly the thermocouple and the thermostat control was replaced by the homeowner.

Gunnar,

He says he can't get the pilot to stay lit. This is only occurs though in the afternoon. If he waits till the early morning, it can be lit and remain lit at the time, but comes home that afternoon and its out again.

Heck it could be those gremlins.

rick

Rick,
Had a similar situation, replaced the thermocouple and still the pilot would not stay lit. Had to replace the gas valve and all was fine.
Lee

I would check for trash in the pilot orifice. The hole is tiny and it doesn't take much to block it. Spider webs can cause this problem also.

Years ago I had a similar situation. Turns out when the attic fan kicked on, the pilot would go out.

After sitting in a 100+ degree attic this afternoon checking out this water heater, I came to the conclusion it was the power ventilator causing the problem.

Seems the homeowner had added (2) more power ventilators since my original inspection.

rick

If you get flue gas spillage, the CO2 will fall to the floor snuffing out the flame. I've seen this several times. Get a pro in there to check for CO and improper venting.
Bob

Seems the homeowner had added (2) more power ventilators since my original inspection.

So basically, all that power trying to suck the hot air out pulled air down the w/h flue? That's some powerful stuff. Was the draft hood still in place on the w/H?

I'll bet they did not all any soffit vents to balance out the exhaust. Seems like I remember reading that somewhere... Oh yeah, the manufacturer's instructions!

Rick were you just being a good guy or were they trying to throw this back on you?

Originally Posted by Rick Hurst

After sitting in a 100+ degree attic this afternoon checking out this water heater, I came to the conclusion it was the power ventilator causing the problem.

Sounds like no fun at all. Was it windy up there with all of those fans going?

Jim,

This was a young man with his first home and I was trying to help him out. He was not complaining at all, but was just wondering what was going on.

Actually he has already sent me several referrals in the last 2 months, so I was just going out of my way to help him out.

Gunnar,

Yeah, when those fans came on the breeze was nice except for the fiberglass dust particles.

Mask or not, the stuff still gets to you.

rick

Originally Posted by Rick Hurst

when those fans came on the breeze was nice except for the fiberglass dust particles.

Just think what he's doing to the living space below ... sucking all the conditioned air up into the now depressurized attic ... which depressurizes the living space, sucking in all the hot humid air outside ... which (I am sure) now costs him more to condition the conditioned space than ever before, add to that the energy to operate those two fans and he likely has one big net energy loss.

Net energy loss.

Moisture in the house (being drawn in from outside).

Wonder what the depressurized attic does to the ductwork, which is intended to be sealed against the positive pressure within the duct, but now has negative pressure outside the duct as well - is the duct sealed to resist that too?

The more I think about it, the more problems I think of.

Originally Posted by Rick Hurst

After sitting in a 100+ degree attic this afternoon checking out this water heater, I came to the conclusion it was the power ventilator causing the problem.

Seems the homeowner had added (2) more power ventilators since my original inspection.

rick

Rick

I just noticed you mentioned two more power fans in the attic for ventilation. Say what??? So this makes three power vents in the attic. Nothing like a little to much attic ventilation. No wonder why the pilot won't stay lit.

Unless I missed something else some where, How big is this attic. I am all for plenty of ventilation but if she is sucking to much air thru there the thermal factor of the insulation and the draw to the inside of the home will be way to much and here efficiency will be shot to hell.